In complex hydraulic systems wherein a large number of hydraulic components are utilized and wherein the functions of the components are inter-related, fluid filtration becomes an extremely important consideration. In such systems, a very high fluid flow rate is often required and it becomes imperative to assure that an extremely clean hydraulic fluid is utilized.
Oftimes hydraulic fluid becomes contaminated during transportation from its source to the user facility. If such contaminated fluid is added directly to an unfiltered portion of a high-rate hydraulic system, component damage can result before such contaminated fluid is passed through the filtration system provided. Conventional systems have no provision for the immediate filtration of such additive fluid. Furthermore, when high flow rates are desired, a large filtration area must be provided so that differential pressure across the individual filter elements, due to contaminant removal from fluid flow, may be kept low to assure that efficient operation of the components will not be impeded.
Also, in conventional systems, some sort of relief valving arrangement is usually provided to avoid excessive pressure buildup and so that if the filtration unit becomes clogged, unfiltered fluid can by-pass into the fluid circuit. While such unfiltered relief flow does protect against damage due to excessive pressure, the aforementioned problems of contamination of the components are still present.
Many conventional systems which utilize a by-pass or relief valve arrangement in conjunction with a filtration unit usually prove somewhat unaccessible for servicing or component replacement.